I registered for a developer edition account to use the REST API for a project. I am not able to get the authentication done.

I get  

{"error":"unknown_error","error_description":"retry your request"}

message. This happens only for the developer account. I tried the same authentication method on a professional (trial) and a group edition with success.

 Below is the command i use. I made sure i am using the correct client_id/client_secret/password+securityToken

curl https://login.salesforce.com//services/oauth2/token -d "grant_type=password&client_id={client_id}&client_secret={secret}&username={uname@email.com}&password={password+SecurityToken}"

When requesting an access token from https://login.salesforce.com/services/oauth2/token, I get the response:

unknown error, please retry your request

I seem to be making a well-formatted request with proper credentials, but I get this mysterious error.  Has anybody seen this and can anybody help?

Many thanks,

MagneticDisk